FREQUENT GENE DELETIONS IN POTENTIALLY MALIGNANT ORAL LESIONS

Some oral cancers are preceded by premalignant lesions which include l eucoplakia and erythroplakia. At present there are no reliable markers to identify lesions that may progress to malignancy. We have analysed 30 potentially malignant oral lesions for deletions at chromosomal re gions that harbour tumour-suppressor genes for oral cancer. A total of 16 of 30 cases (53%) showed loss of heterozygosity (LOH) or allele im balance at TP53, DCC, 3p21.3-22.1 or 3p12.1-13. These genetic alterati ons were detected in dysplastic lesions but not in histologically norm al mucosa and may be early events in the carcinogenic process. A total of 64% of dysplastic lesions that recurred during the study showed LO H or allele imbalance in the initial biopsy and the number of genetic abnormalities increased in the tumours that developed. This type of mo lecular profiling may help to identify patients with lesions that may recur or acquire additional genetic events and progress to malignancy.